“… music notation for everyone”.
LilyPond is an automated engraving system by Han-Wen Nienhuys, Jan Nieuwenhuizen and others. It formats music beautifully and automatically, and has a friendly syntax for its input files. It is Free Software (‘open source’). It prints music in the best traditions of classical engraving with minimum fuss. Don’t waste time on tuning spacing, moving around symbols, or shaping slurs. Impress friends and colleagues with sharp sheet music!